Statistical analysis of monitoring data regarding urinary iodine level of infants and babies in Ningxia in 2009

Objective To determine urinary iodine level among babies and infants aged 0-30 months in Ningxia, and to provide scientific evidence for strengthening iodine supplement or decreasing salt iodine level in special population. Methods One thousand four hundred and eighty-three babies and infants were selected randomly from 664 administrative villages of 22 counties (city or district) by two-stage sampling method. Urinary iodine was tested with the arsenic cerium catalysis spectrophotometric method and related influencing factors were analyzed. Results Urinary iodine median was 216.5 μg/L of the whole autonomous region, and the value that was lower than 100 μg/L, accounted for 19.1%(283/1483), 100 - 300 μg/L accounted for 49.3%(731/1483), higher than 300 μg/L, accounted for 31.6% (469/1483). Urinary iodine median was in 130.6 - 328.4 μg/L of all counties, which was higher than 100 μg/L. The urinary iodine median of men(223.2 μg/L) was slightly higher than that(210.2 μg/L) of female, no significant difference was observed(Z = - 1.76, P > 0.05). Urinary iodine level changed little when child was younger than one year old(Z = - 0.624, P > 0.05). Then the value dropped gradually after one year old(χ2 = 13.59, P < 0.05), decreased with age by month, and the proportion of the value smaller than 100 μg/L was increased gradually. Urinary iodine level(257.5 μg/L) of child whose mother had taken iodine oil pills was higher than that (221.2 μg/L) of child whose mother had significant difference was observed(Z = - 2.54, P < 0.05). The urinary iodine level (239.1 μg/L) of child who received breast feeding was higher than that (204.2 μg/L) of child without breast feeding among one year old and younger infants and babies, significant difference was observed (Z = - 2.74, P < 0.05). Conclusions Current iodine level in iodized salt is probably higher than suitable in Ningxia, and the value could be decreased. It is unnecessary to strengthen iodine supplement procedure in special population other than people in Xiji county. Key words: Iodine; Infants and babies; Nutrition status